Weakly coordinating anions containing polyfluoroalkoxide ligands

ABSTRACT

A compound comprising a polyfluorinated anion and the use thereof is provided. Specifically, the present invention provides a compound comprising an anion which comprises a polyfluorinated alkoxide coordinated to a transition metal, or a Group III, IV or V element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/123,599, filed Mar. 10, 1999.

This application is also related to, but does not claim priority from,U.S. patent application Ser. No. 09/151,852, filed Sep. 11, 1998, whichclaims priority based on U.S. Provisional Patent Application Ser. No.60/058,524, filed Sep. 11, 1997, disclosures of which are incorporatedherein by reference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The U.S. Government has a paid-up license in this invention and theright in limited circumstances to require the patent owner to licenseothers on reasonable terms as provided for by the terms of Grant No.CHE-9628769 awarded by National Science Foundation.

FIELD OF THE INVENTION

The present invention relates to a compound containingpolyfluoroalkoxides and the use thereof, in particular, for use as anelectrolyte in batteries and other electrochemical devices.

BACKGROUND OF THE INVENTION

A compound containing a weakly coordinating anion (i.e., an anion thatcoordinates only weakly with a cation) is useful in a variety ofapplications including as an electrolyte and a counter-ion for acatalyst in a variety of organic reactions. Some of the useful catalystscontaining a weakly coordinating anion are described by Barbarich, etal. in “LiAl(OC(Ph)(CF₃)₂)₄: A Hydrocarbon-Soluble Catalyst ForCarbon-Carbon Bond-Forming Reactions”, Organometallics, 1996, 15, 3776,which is incorporated herein in its entirety.

Investigations of very reactive metal and nonmetal cations continues tospur the development of new weakly coordinating anions. See, forexample, Bochmann, Angew. Chem., Int. Ed. Engl. 1992, 31 1181; Strauss,Chem. Rev. 1993, 93, 927, Strauss, Chemtracts-Inorganic Chem. 1994, 6,1;and Seppelt, Angew. Chem., Int. Ed. Engl. 1993, 32, 1025. One of themost important uses of weakly coordinating anions is to enhance thecatalytic activity of metal cations. Two examples that have receivedconsiderable attention recently are metallocene-catalyzed olefinpolymerization, and lithium-catalyzed Diels-Alder reactions and1,4-conjugate addition reactions. See Turner, European Patent Appl. No.277,004, 1988; Pellecchia et al., Makromol. Chem., Rapid Commun. 1992,13, 265; DuBay et al., J. Org. Chem. 1994, 59, 6898; Saidi et al., Chem.Ber. 1994, 127, 1761; Kobayashi et al., Chem. Lett. 1995, 307; and Araiet al., Angew. Chem., Int. Ed. Engl. 1996, 15, 3776.

Useful anions must not only be weakly coordinating, they must also bestable with respect to oxidation and/or fragmentation in the presence ofhighly electrophilic cations. In addition, an ideal weakly coordinatinganion should have a single negative charge dispersed over a largesurface composed of relatively nonpolar bonds to weakly basic atoms suchas hydrogen or the halogens. Weakly coordinating anions which conform tomany, but not all, of these criteria include B (Ar_(f))₄ ⁻ (Ar_(f)=C₆F₅or 3,5-C₆H₃(CF₃)₂), CB₁₁H_(12-n)X_(n) ⁻ (X=H, Me, Cl, Br, F or I),CB₉H_(10-n)X_(n) ⁻ (X=H, F, Cl, or Br), and M(OTeF₅)_(n) ⁻ (n=4, M=B;n=6, M=Nb, Sb).

All of the anions mentioned above have limitations. Some are toostrongly coordinating for specific applications. Some are unstable underthe harsh chemical conditions where they would be employed. For example,the fluorinated derivatives of BPh₄ ⁻ can react with stronglyelectrophilic cations, causing (i) cleavage of a C—F bond and formationof a bond between the fluorine atom and the cation or (ii) transfer of afluoroaryl group to the cation. In either case, the cation is no longerreactive or catalytically active.

Other weakly coordinating anions, such as ClO₄ ⁻, BF₄ ⁻, PF₆ ⁻, SbF₆ ⁻,B(OTeF₅)₄ ⁻, and Nb(OTeF₅)₆ ⁻, are not thermally and/or hydrolyticallystable. In addition, lithium salts of such anions, including LiCF₃SO₃,have low electrical conductivity in some organic solvents, especiallyorganic solvents that are stable in the presence of strong reducingagents such as metallic lithium and related lithium-containing batteryanode solutions. Furthermore, some lithium salts, such as lithiumtriflate (LiCF₃SO₃), cause corrosion of the aluminum current collectorsin batteries, while some lithium salts, such as LiPF₆, are known to beunstable at temperatures as low as 70° C. and decompose over time.

Still other anions containing boron atoms, and anions containing acarbon atom and a cluster of boron atoms, such as carboranes (e.g., CB₅,CB₉, CB₁₁), are not particularly weakly coordinating because the saltsformed therefrom contain at most only one fluorine atom which is bondedto a boron atom.

Recently, polyfluorinated carborane anions that are weakly coordinatingand are thermally and/or hydrolytically stable have been disclosed incommonly assigned U.S. patent application Ser. No. 09/049,420, filedMar. 27, 1998. In addition, one particular class of compounds containingpolyfluoroalkoxide ligands and the use thereof has been disclosed incommonly assigned PCT Patent Application No. PCT/US98/19268, filed Sep.11, 1998, and commonly assigned U.S. patent application Ser. No.09/151,852, filed Sep. 11, 1998, disclosures of which are incorporatedherein by reference in their entirety.

Despite the recent advances in weakly coordinating anions, there stillis a need for new weakly coordinating anions. There is also a need forweakly coordinating anions having a high electrical conductivity in anorganic solvent. There is also a need for weakly coordinating anionsthat are stable in solution and in the solid state.

SUMMARY OF THE INVENTION

One embodiment of the present invention provides a compound comprising amonoanion of the formula:

and uses thereof,

where

M₁ is a transition metal, or a Group III, IV or V element;

each Z is independently O, S, or NR₆R₇;

each X is independently a halide;

each R₁ is independently a bond or C₁-C₄ alkylene;

each of R₂, R₃and R₄ is independently H, F, fluorinated C₁-C₁₀ alkyl,fluorinated C₄-C₂₀ aryl, C₃-C₁₀ cycloalkyl, fluorinated C₃-C₁₀cycloalkyl, C₁-C₁₀ alkyl or C₄-C₂₀aryl, provided at least one of R₂, R₃and R₄ is F, fluorinated C₁-C₁₀ alkyl, fluorinated C₃-C₁₀ cycloalkyl, orfluorinated C₄-C₂₀ aryl;

each R₅ is independently fluorinated C₁-C₁₀ alkyl, fluorinated C₄-C₂₀aryl, C₄-C₂₀ aryloxide, fluorinated C₄-C₂₀ aryloxide, C₁-C₁₀ alkoxide orfluorinated C₁-C₁₀ alkoxide;

each of R₆ and R₇ is independently H or C₁-C₁₀ alkyl;

each of a, b and c is independently an integer from 0 to 4,

provided the sum of a, b and c is an integer from 2 to 8; and n is 1 or2; and

provided that when R₂ is a fluorinated C₁ -C₄ alkyl, R₁ is a bond, b,and c are 0, and R₃ is C₁-C₁₀ alkyl or fluorinated C₄-C₁₀ alkyl then R₄is F, fluorinated C₁-C₁₀ alkyl or fluorinated C₄-C₂₀ aryl.

Another embodiment of the present invention provides a compoundcomprising an anion of the formula:

wherein

M₁ is a transition metal, or a Group III, IV or V element;

L is a halide, C₁-C₁₀ alkyl, fluorinated C₁-C₁₀ alkyl, C₄-C₂₀ aryl,fluorinated C₁-C₂₀ alkyl or a moiety of the formula −Z₃-R₁₁;

d is an integer from 0 to 4;

e is an integer from 1 to 3;

the sum of d and e is an integer from 1 to 6;

n is 1 or 2;

each of Z₁, Z₂ and Z₃ is independently O, S, or NR₆R₇;

each of R₆ and R₇ is independently H or C₁-C₁₀ alkyl;

each R₉ is independently C₁-C₃₀ alkylene, fluorinated C₁-C₃₀ alkylene,substituted C₁-C₃₀ alkylene, C₃-C₁₀ cycloalkylene, fluorinated C₃-C₁₀cycloalkylene, C₄-C₂₀ arylene or fluorinated C₄-C₂₀ arylene;

each of R₈ and R₁₀ is a bond, or a moiety of the formula—[C(R₁₂R₁₃)]_(x)—;

each x is independently an integer from 1 to 4;

each of R₁₂ and R₁₃ is independently H, F, C₁-C₄ alkyl or fluorinatedC₁-C₄ alkyl; and

each R₁₁ is independently C₁-C₁₀ alkyl, fluorinated C₁ -C₁₀ alkyl,C₄-C₂₀ aryl, or fluorinated C₄-C₂₀ aryl;

provided at least one of R₈ and R₁₀ is a moiety of the formula—C(R₁₂R₁₃)— and at least one of R₁₂ and R₁₃ is F or fluorinated C₁-C₄alkyl.

The present invention also provides an electrolyte for anelectrochemical device, comprising the anion of the above describedformula having a counter cation M where M is a metal cation, aphosphonium cation, an ammonium cation or a sulfonium cation. PreferablyM is Li cation.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a compound comprising an anion of theformula:

and uses thereof, where M₁ is a transition metal, or a Group III, IV orV element, preferably M₁ excludes Cu; each Z is independently O, S, orNR₆R₇; each X is independently a halide; each R₁ is independently a bondor C₁-C₄ alkylene; each of R₂, R₃ and R₄ is independently H, F,fluorinated C₁-C₁₀ alkyl, fluorinated C₄-C₂₀ aryl, C₃-C₁₀ cycloalkyl,fluorinated C₃-C₁₀ cycloalkyl, C₁-C₁₀ alkyl or C₄-C₂₀ aryl, provided atleast one of R₂, R₃ and R₄ is F, fluorinated C₁-C₁₀ alkyl, fluorinatedC₃-C₁₀ cycloalkyl, or fluorinated C₄-C₂₀ aryl; each R₅ is independentlyfluorinated C₁-C₁₀ alkyl, fluorinated C₄-C₂₀ aryl, C₄-C₂₀ aryloxide,fluorinated C₄-C₂₀ aryloxide, C₁-C₁₀ alkoxide or fluorinated C₁-C₁₀alkoxide; each of R₆ and R₇ is independently H or C₁-C₁₀ alkyl; each ofa, b and c is independently an integer from 0 to 4, provided the sum ofa, b and c is an integer from 2 to 8; and n is 1 or 2; provided thatwhen R₂ is a fluorinated C₁-C₄ alkyl, R₁ is a bond, b, and c are 0, andR₃ is C₁-C₁₀ alkyl or fluorinated C₁-C₁₀ alkyl then R₄ is F, fluorinatedC₁-C₁₀ alkyl or fluorinated C₄-C₂₀ aryl.

The present invention also provides a compound comprising an anion ofthe formula:

where M₁ is a transition metal, or a Group III, IV or V element; L is ahalide, C₁-C₁₀ alkyl, fluorinated C₁-C₁₀ alkyl, C₄-C₂₀ aryl, fluorinatedC₄-C₂₀ alkyl or a moiety of the formula —Z₃—R₁₁; d is an integer from 0to 4; e is an integer from 1 to 3; the sum of d and e is an integer from1 to 6; n is 1 or 2; each of Z₁, Z₂ and Z₃ is independently O, S, orNR₆R₇; each of R₆ and R₇ is independently H or C₁-C₁₀ alkyl; each R₉ isindependently C₁-C₃₀ alkylene, fluorinated C₁-C₃₀ alkylene, substitutedC₁-C₃₀ alkylene, C₃-C₁₀ cycloalkylene, fluorinated C₃-C₁₀ cycloalkylene,C₄-C₂₀ arylene or fluorinated C₄-C₂₀ arylene; each of R₈ and R₁₀ is abond, or a moiety of the formula —[C(R₁₂R₁₃)]_(x)—; each x isindependently an integer from 1 to 4; each of R₁₂ and R₁₃ isindependently H, F, C₁-C₄ alkyl or fluorinated C₁-C₄ alkyl; and each R₁₁is independently C₁-C₁₀ alkyl, fluorinated C₁-C₁₀ alkyl, C₄-C₂₀ aryl, orfluorinated C₄-C₂₀ aryl; provided at least one of R₈ and R₁₀ is a moietyof the formula —C(R₁₂R₁₃)— and at least one of R₁₂ and R₁₃ is F orfluorinated C₁-C₄ alkyl.

Preferably, the compound of the present invention has at least twopolyfluorinated alkoxide groups bonded to M₁. As used herein, a“polyfluorinated anion” refers to an anion of the above describedformula.

The polyfluorinated anions of the present invention themselves do notnecessarily comprise chemical compounds. Indeed, in an isolablecompound, anions must be paired with cations to maintainelectroneutrality. Thus, compounds of the present invention are, moreaccurately, of the formulas:

where M is a cation having a valence of from 1 to 4. M can be any cationincluding a cation derived from an alkali metal; alkaline-earth metal;transition metal such as Ag, Zn, Cu, Co, Fe, Mn, Cr, V, Ti, Zr, Rh, Pd,Cd, Hg, Os, Pt, Y, Nb, Sc, Ta, Hf, and Mo; lanthanide and actinideseries metal; ammonium moieties such as ammonium, tetrahydrocarbylammonium, e.g., tetrabutyl ammonium and tetraethyl ammonium,trihydrocarbyl ammonium, e.g., triethyl ammonium, diisopropyl ethylammonium and trimethyl ammonium, dihydrocarbyl ammonium, nitrogenheteroaromatic cation such as 2,6-lutidinium, methyl 2,6-lutidinium,methyl pyridinium and pyridinium, and imminium cation; phosphoniummoieties including tetraalkylphosphonium, tetraaryl phosphonium andphosphonium ions containing a mixture of alkyl and aryl groups;sulfonium moieties such as sulfonium ions containing alkyl, aryl ormixtures thereof; and other suitable cations such as thallium.Furthermore, M can be a relatively stable carbocation such as a tritylmoiety and related carbocations (e.g., R₃C⁺); and other known cationssuch as hydronium (H₃O⁺), H₅O₂ ⁺, (Et₂O)_(n)H⁺, H₉O₄ ⁺, and formylium(HCO⁺). Preferably, the cation (i.e., M) is selected from the groupconsisting of thallium, alkali metal and alkaline earth metal cations,ammonium, monohydrocarbyl ammonium, dihydrocarbyl ammonium,trihydrocarbyl ammonium, tetrahydrocarbyl ammonium, nitrogenheteroaromatic cation, tetrahydrocarbyl phosphonium, hydronium,formylium, and trityl and related carbocations; more preferably from thegroup consisting of trityl and related carbocations, thallium,tetrahydrocarbyl ammonium, alkali metal cations, and nitrogenheteroaromatic cation; and most preferably from the group consisting oftrityl, Li⁺, Tl⁺, 2,6-lutidinium, tetraethylammonium, sodium, potassium,and N-methyl-2,6-lutidinium. As used in this invention, a “hydrocarbyl”refers to a compound having at least one carbon atom. Such compoundsinclude aryl, alkyl, alkenyl and alkynyl. Moreover, hydrocarbyl can bestraight chain, branched, or cyclic. Hydrocarbyl can also be substitutedwith other non hydrogen or carbon atoms such as halide, oxygen, sulfur,nitrogen or phosphorus.

It will be appreciated that a molar ratio of a cation to apolyfluorinated anion of the present invention depends on the valence ofthe cation. This is reflected in the values p and k, for example, ifboth the cation and the anion are monovalent, then k and p are 1, andthere will be a 1:1 molar ratio between the cation and thepolyfluorinated anion of the present invention. Whereas if the cation isdivalent and the anion is monovalent, then k is 2 and p is 1, and therewill be a 1:2 molar ratio between the cation and the polyfluorinatedanion of the present invention. Preferably, k is an integer from 1 to 4,more preferably 1 to 3, still more preferably k is 1 or 2, and mostpreferably 1. Preferably p is 1 or 2 and more preferably 1.

It should be appreciated that because the polyfluorinated anions of thepresent invention are weakly associating (i.e., coordinating) anions, acation associated with a polyfluorinated anion can be readily exchangedwith another cation by any of the known methods including ion exchangechromatography and other ion exchange methods.

As used in this invention, Group III, IV and V elements are thoseelements which are listed in the Group III, IV and V of the periodictable, respectively. For example, Group III elements are B, Al, Ga, Inand Tl; Group IV elements are C, Si, Ge, Sn, and Pb; and Group Velements are N, P, As, Sb and Bi.

With reference to formulas I-IV described herein:

Preferably M₁ is selected from the group consisting of Al, B, V, Ti, Si,Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf and Sb, morepreferably from the group consisting of Al, B, V, Ti, Si, Zr, Ge, Sn, Y,Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf and Sb, still more preferably from thegroup consisting of Al, B, Nb and Ta, and most preferably from the groupconsisting of Al and B.

Preferably, Z, Z₁, Z₂ and Z₃ are O.

Preferably n is 1.

Preferably a is 1, 3 or 4, more preferably 4.

Preferably b is 0 or 1.

Preferably c is 0 or 3.

Preferably the sum of a, b and c is an integer from 2 to 8, morepreferably an integer from 4 to 8, still more preferably an integer from4 to 6, and most preferably 4.

Preferably X is fluoride.

Preferably R₅ is fluorinated C₄-C₂₀ aryl or fluorinated C₄-C₂₀aryloxide, more preferably fluorinated phenyl or phenoxide, and mostpreferably 2-trifluoromethylphenoxide, 3-trifluoromethylphenoxide,4-trifluoromethylphenoxide, pentafluorophenoxide, or pentafluorophenyl.

Preferably R₁ is a bond or methylene.

Preferably each of R₂, R₃ and R₄ is independently H, F, fluorinatedC₁-C₄ alkyl, C₄-C₂₀ aryl or fluorinated C₄-C₂₀ aryl. More preferablyeach of R₂, R₃ and R₄ is independently H, F, trifluoromethyl, phenyl,4-methylphenyl, methyl, n-butyl, 4-tert-butylphenyl,3,5,-di(trifluoromethyl)phenyl, 3,5,-dimethylphenyl,2,4,6-tri(trifluoromethyl)phenyl,4-(triisopropylsilyl)-2,6-di(trifluoromethyl)phenyl, tert-butyl,cyclohexyl or pentafluorophenyl.

Preferably L is a halide or a moiety of the formula —Z₃—R₁₁, C₁-C₁₀alkyl, fluorinated C₁-C₁₀ alkyl, C₄-C₂₀ aryl or fluorinated C₄-C₂₀alkyl; more preferably L is F, pentafluorophenyl, or a moiety of theformula —Z₃—R₁₁.

Preferably d is an integer from 0 to 6, more preferably an integer from0 to 4, and most preferably d is 0 or 2.

Preferably e is an integer from 1 to 4, more preferably an integer from1 to 2 and most preferably e is 2.

Preferably, the sum of d and e is an integer from 1 to 6, morepreferably 2 to 4.

Preferably R₁₁ is fluorinated C₁-C₁₀ alkyl.

Preferably R₉ is substituted or unsubstituted P₁,P₂-substituted aryleneor fluorinated arylene, or substituted or unsubstitutedP₁,P₂-substituted cycloalkylene or fluorinated cycloalkylene, such ascyclopentylene, and preferably cyclohexylene. As used in this invention,P₁,P₂-substituted arylene/cycloalkylene refers to anarylene/cycloalkylene moiety in which —Z₁—R₈— and —Z₂—R₁₀— groups are inP₁- and P₂-positions of the arylene/cycloalkylene moiety, respectively.Thus, for example, 1,2-substituted phenylene refers to a phenylene grouphaving —Z₁—R₈— in the 1-position of the phenyl ring and —Z₂—R₁₀— groupin the 2-position of the phenyl ring. “Substituted or unsubstituted”refers to the presence or absence of one or more substituents on thephenyl (or other appropriate) ring moiety, respectively. Suchsubstituents can be F, Cl; Br; I; an alkyl group including cyclic alkyland alkyl groups containing F, Cl, Br and/or I; and an aryl groupincluding aryl groups containing F, Cl, Br and/or I and heteroarylgroups. For an electrolyte, R₉ can also be C₁-C₄ alkylene or fluorinatedC₁-C₄ alkylene, in particular —C(CF₃)₂— moiety.

Preferably x is a bond or 1.

Preferably each of R₁₂ and R₁₃ are independently fluorinated C₁-C₄alkyl. More preferably R₁₂ and R₁₃ are independently trifluoromethyl orperfluoroethyl, most preferably R₁₂ and R₁₃ are trifluoromethyl.

Alkyl groups according to the present invention are aliphatichydrocarbons which can be straight or branched chain groups. Alkylgroups optionally can be substituted with one or more substituents, suchas Cl, Br, I, alkenyl, alkynyl, aryl, hydroxy, alkoxy, carboxy, oxo orcycloalkyl. There may be optionally inserted along the alkyl group oneor more oxygen, sulfur or substituted or unsubstituted nitrogen atoms.Exemplary alkyl groups include methyl, ethyl, i-propyl, n-butyl,t-butyl, chloromethyl, trichloromethyl, and pentafluoroethyl. Alkylgroups containing at least one fluorine is specifically refered hereinas fluorinated alkyl groups.

Aryl groups are carbocyclic or heterocyclic aromatic ring moieties. Arylgroups can be substituted with one or more substituents, such as a Cl,Br, I, alkenyl, alkyl, alkynyl, hydroxy, alkoxy or cycloalkyl. Exemplaryaryl groups include, phenyl, p-methylphenyl, p-tert-butylphenyl,thienyl, furanyl, pyrimidinyl, pyridyl, oxazolyl, isoxazolyl, andthiophenyl. Aryl groups containing at least one fluorine is specificallyrefered herein as fluorinated aryl groups.

M₁ of the polyfluorinated anion of the present invention may contain amixture of polyfluorinated alkoxide and non-fluorinated alkoxideligands.

Specific polyfluoroalkoxide ligands for anion of formula I (i.e.,compound of formula III), include, but are not limited to, the followingligands:

a polyfluoroalkoxide ligand where Z is O, R₁ is methylene, b and c are0, a is 4, and R₂, R₃ and R₄ are F; and

polyfluoroalkoxides where Z is O and R₁ is a bond, and

R₂ is trifluoromethyl, and each of R₃ and R₄ is independently phenyl ormethyl;

R₂, R₃ and R₄ are trifluoromethyl;

R₂ is trifluoromethyl, R₃ is phenyl, and R₄ is phenyl orpentafluorophenyl; and

R₂ and R₃ are phenyl, and R₄ is pentafluorophenyl.

Specific polyfluoroalkoxide ligands for anion of formula II (i.e.,compound of formula IV), include, but are not limited to, the followingligands:

n is 1 and the —Z₁—R₈—R₉—R₁₀—Z₂— moiety comprises:

 where each of R₁₄, R₁₅, R₁₆, and R₁₇ is independently H, C₁-C₁₀ alkyl,fluorinated C₁-C₁₀ alkyl, C₄-C₂₀ aryl, or fluorinated C₄-C₂₀ aryl.Preferably, R₁₄ and R₁₇ are trifluoromethyl, R₁₅ is H, and R₁₆ isphenyl.

Unlike other anions containing chelating dialkoxide groups, compounds IIand IV of the present invention have improved stability (thermal,hydrolytic and electrochemical) lower toxicity, and/or higher syntheticyields. Moreover, compounds of the present invention, in particularlithium salts, have high conductivity making them particularly useful aselectrolytes in electrochemical devices.

A variety of counter-cation species, including metal cations such as Li,K, Na, Mg, Ca, and Cs; trityl cation; pyridinium cations such as2,6-pyridinium cation; and 2,6-lutidinium cation, can be prepared fromthe anions of the present invention. For example, by cation-exchangereaction, the trityl (CPh₃ ⁺) salt can be prepared by metathesis of Lisalt of the anions with CPh₃Cl in 1,2-dichloroethane.

Without being bound by any theory, it is believed that the highconductivity of lithium salts of the compounds of the present inventionis due to Li⁺ ion being weakly bonded to several alkoxide oxygen atomsand possibly being bonded to several CF₃-group fluorine atoms, similarto Tl⁺ ions in Tl₂Zr(HFIP)₆. In contrast, the Li⁺ ion in theunfluorinated salt LiNb(OEt)₆ is believed to be strongly bonded to onlyfour ethoxide oxygen atoms from two adjacent Nb(OEt)₆ ⁻ anions forming apseudo-tetrahedral LiO₄ core.

Compounds containing the polyfluorinated anion of the present inventionhave high electrical conductivity making them particularly useful aselectrolytes for electrochemical devices. Exemplary electrochemicaldevices include batteries, such as lithium batteries or lithium ionbatteries for a variety of applications; other type of batteries; fuelcells; electrical double layer capacitors; sensors; and electrochromicdisplays. Such electrochemical devices can be used in a variety ofapplications including electrochemical devices for electric vehicles,lap top computers, and other applications requiring an energy source. Astable 1 shows, lithium salts of the polyfluorinated anions of thepresent invention have high electrical conductivities in organicsolvents. Specifically, the compounds of the present invention have highelectrical conductivity in DME compared to other fluorine-containinglithium salts such as LiOTf.

TABLE 1 Electrical Conductivity¹ Conc. Sol- Conductivity Eq.conductivity Compound (M) vent (mS cm⁻¹) (S cm² mol⁻¹) Li(HFIP) 0.0100DME −0 LiOTf 0.0100 DME 0.00390 0.390 LiOTf/1.36 eq. crown 0.0100 DME0.00700 0.700 LiOTf/>50 eq. crown 0.0100 DME 0.0310 3.10 LiOTf 0.0100 PC0.195 19.5 LiB (C₆F₅)₃ (HFIP) 0.0100 DME 0.176 17.6 LiB (C₆F₅)₃ (DPTE)0.0100 DME 0.129 12.9 LiB (C₆F₅)₃ (PFTB) 0.0100 DME 0.137 13.7 LiB(HFPOP)₂ 0.0100 DME 0.137 13.7 LiB (HFPOP)₂ 0.100 DME 1.58 15.8 LiB(HFPOP)₂ 0.200 DME 3.05 15.2 LiB (HFPOP)₂ 0.300 DME 4.49 15.0 LiB(HFPOP)₂ 0.400 DME 5.30 13.2 LiB (HFPOP)₂ 0.500 DME 5.88 11.8 LiB(HFPOP)₂ 0.600 DME 5.83 9.7 LiB (HFPOP)₂ 0.0100 PC 0.133 13.3 LiB(HFAPOP)₂ 0.0100 DME 0.160 16.0 LiB (HFAPOP)₂ 0.100 DME 1.77 17.7 LiB(HFAPOP)₂ 0.300 DME 4.22 14.1 LiB (HFAPOP)₂ 0.500 DME 4.35 8.69 LiB(HFTPOP)₂ 0.0100 DME 0.218 21.8 LiB (HFTPOP)₂ 0.500 DME 8.23 16.5 LiAl(HFIP)₄ 0.0100 DME 0.183 18.3 LiAl (TFTB)₄ 0.0100 DME 0.0693 6.93 LiAl(DPTE)₄ 0.0100 DME 0.205 20.5 ¹HFIP⁻ = OCH(CF₃)₂ ⁻; DPTE⁻ =OC(CF₃)(C₆H₅)₂ ⁻; TFTB⁻ = OC(CF₃)(CH₃)₂ ⁻; PFTB⁻ = OC(CF₃)₃ ⁻; HFPOP⁻² =OC(CF₃)₂(C₆H₄O)⁻²; HFAPOP⁻² = # OC(CF₃)₂[C₆H₂(CH₃)(C₄H₉)O]⁻²; HFTPOP⁻² =OC(CF₃)₂(C₆HF₃O)⁻²; OTf⁻ = CF₃SO₃ ⁻; crown = 12-crown-4; PC = propylenecarbonate; DME = 1,2-dimethoxyethane.

Particularly useful lithium salts of the compounds of the presentinvention in batteries include LiB(HFPOP)₂, LiB (HFAPOP)₂, and LiB(HFTPOP)₂.

Again referring to Table 1, the lithium salts of the polyfluorinatedanions of the present invention are at least about two orders ofmagnitude higher in electrical conductivity than lithium triflate. Thus,the amount of a compound of the present invention required in anelectrochemical device to achieve a similar electrical conductivity inan organic solvent such DME is about 1% of the amount of otherfluorine-containing electrolytes such as LiCF₃SO₃.

A lithium salt of the polyfluorinated anion of the present invention hasan electrical conductivity of at least about 4 μScm⁻¹ in DME at about0.01 M concentration at about 25° C., preferably at least about 60μScm⁻¹, more preferably at least about 150 μScm⁻¹, and most preferablyat least about 180 μScm⁻¹.

Without being bound by any theory, it is believed that the weak bondsbetween the Li⁻ cation and the CF₃ groups are responsible for the highelectrical conductivity in low dielectric solvents. Indeed, it isbelieved that the high degree or fluorination and the weak coordinationbetween the Li⁺ cations in the C-F bonds differentiate the lithium saltsof the present invention from other fluorine-containing lithium salts.

The electrochemical stability of a representative compound is shown inTable 2 below. Specifically, Table 2 lists anodic stability of acompound containing a chelating group HFTPOP, e.g., a bidentate group.The anodic stability shows the relative stability of the compound andthe potential for oxidation of an anode containing the compound relativeto lithium.

TABLE 2 Anodic Stability Compound Solvent Conc. (M) Potential vs. Li/Li⁺(V) LiB (HFTPOP)₂ DME 0.1 4.7 LiAl (HFPP)₄ DME 0.07 >5.2 Conditions:Sweep rate: 5 mV/s; T = 25° C.; Reference electrode: Li wire; Workingelectrode Pt; Counter electrode: Pt mesh.

The polyfluorinated anions of the present invention can also be used ina variety of organic reaction catalysts where a weakly coordinatinganion improves the yield, selectivity and/or the rate of catalyticreaction by the corresponding cation including in catalysts forconjugate additions and Diels-Alder reactions. The compounds of thepresent invention comprise a weakly coordinating anion, i.e.,polyfluorinated anion, which enhances the catalytic activity of theassociated metal cation. Exemplary catalytic reactions that haverecently received a considerable attention are lithium-catalyzedDiels-Alder reactions and lithium-catalyzed 1,4-conjugate additionreactions. As shown below, using LiNb(HFIP)₆, 1, as a catalyst in1,4-conjugate addition reaction of silyl ketene acetal 2 to thesterically encumbered α,β-unsaturated carbonyl compound 3 gave the1,4-addition product 4 in 93% yield.

Reaction conditions: 1,2-dichloroethane (DCE) solvent, 0.1 M of 3, 0.2 Mof 2, 0.01 M of LiNb(HFIP)₆ and 0.01 M of hexamethylphosphoramide (HMPA)at 24° C. for 30 hours.

Formation of only the 1,4-addition product 4 was observed under theseconditions. Interestingly, when HMPA was left out of the reactionmixture, a mixture of 4 and the 1,2-addition product 5 was observedafter only 10 minutes (95% isolated yield, 4:5 mole ratio=1:5). Withoutbeing bound by any theory, it is believed that Li⁺ ion coordinates withHMPA to produce a sterically more hindered enone-lithium ion complex,thus favoring addition of the ketene at a site more distant from thecarbonyl carbon, i.e., 1,4-addition, over addition of the ketene to thecarbonyl carbon, i.e., 1,2-addition reaction. Because lithium compoundsof the present invention are similar to lithium compounds disclosed inPCT Patent Application No. PCT/US98/19268 and U.S. patent applicationSer. No. 09/151,852, lithium compounds of the present invention areexpected to provide a similar reaction selectivity.

A comparison of the ability of LiNb(HFIP)₆ and two other lithiumcatalysts to increase the formation of 1,4-conjugate addition product isshown in Table 3. The weaker Lewis acidity of the Li(HMPA)⁺ complexresults in a decreased reaction rate, which is evidenced by the longerreaction time required when HMPA is added to the reaction mixture. Theresults obtained with LiNb(HFIP)₆ are comparable to the results obtainedwith the very active catalyst LiCo(C₂B₉H₁₁)₂. Product yields weresubstantially lower when LiClO₄ was the catalyst. Furthermore, whenLiClO₄ was employed in the presence of co-catalyst HMPA, the ratio of4:5 improved only to 1.3:1. Without being bound by any theory, it isbelieved that the larger size and/or more weakly coordinating ability ofNb(HFIP)₆ ⁻ to Li⁺ compared with ClO₄ ⁻ is responsible for thedifference in catalytic activity between LiClO₄ and LiNb(HFIP)₆.

TABLE 3 Yields of 1, 4- and 1, 2-addition products 4 and 5,respectively, from lithium-catalyzed reactions between 2 and 3^(a)catalyst co-catalyst^(b) time 4:5 ratio % yield LiNb (HFIP)₆ none 10 min1:5 95% LiNb (HFIP)₆ 0.1 M HMPA 30 h 100:0   93% LiCo (C₂B₉H₁₁)₂ ^(c)none 20 min 1:6 95% LiCo (C₂B₉H₁₁)₂ ^(c) 0.1 M HMPA 32 h 100:0   96%LiClO₄ none 10 min   1:4.5 62% LiClO₄ 0.1 M HMPA 48 h 1.3:1   69%^(a)Reaction conditions: 1,2-dichloroethane, 0.1 M of 3, 0.2 M of 2, 0.1M of catalyst and 0.1 M of co-catalyst, when appropriate, at 25° C.).^(b)HMPA = hexamethylphosphoramide. ^(c)These results are from DuBay etal., J. Org. Chem., 1994, 59, 6898.

The polyfluorinated anions of the present invention that are stericallybulkier, i.e., larger, than Nb(HFIP)₆ ⁻ afford lithium-ion catalyststhat are more regioselective and/or more active in the absence of HMPA.Moreover, enantiomerically enriched polyfluorinated anions of thepresent invention containing a polyfluorinated alkoxide having a chiralcenter afford lithium-ion catalysts that are enantioselective, i.e.,produce an enantiomerically enriched product. A chiral center of acarbon atom, of course, is a carbon atom to which four different groupsare attached; however, the ultimate criterion of chirality of a compoundis nonsuperimposability on the mirror image. Facially selective,enantioselective or stereoselective synthetic reactions are those inwhich one of a set of stereoisomers is formed predominantly orexclusively. Preferably, one isomer is produced in at least about 50percent enantiomeric excess. Enantiomeric excess is the amount ofdifference between one enantiomer and the other enantiomer in theproduct composition. Enantiomeric excess can be expressed by thefollowing formula: %ee=(R−S)/(R+S), where R is amount of one enantiomerand S is the amount of the other enantiomer, for example, %ee of aproduct composition containing 98% of one enantiomer and 2% of the otherenantiomer is 96%. More preferably, one isomer is produced in at leastabout 80 percent enantiomeric excess, still more preferably at leastabout 90 percent enantiomeric excess, even more preferably at leastabout 95 percent enantiomeric excess, and most preferably at least about98 percent excess over the other enantiomer.

Lithium salts of the polyfluorinated anions of the present invention canbe combined or mixed with a polymer to prepare polymeric materials thatexhibit lithium ion conductivity. Such materials, referred to assalt-in-polymer solid electrolytes or solid polymer electrolytes, can beused as electrolytes for solvent-free high-energy-density lithium-basedbatteries. A polymer can also include a linker which allows a directlinkage of the compound of the present invention to the polymericstructure by a chemical bond formation between the polymer and thecompound of the present invention. The polymers useful for the presentinvention have a rubbery physical characteristic. Generally, suitablepolymers have one or more of the following identifyingcharacteristics: 1) ability to dissolve lithium salts of weaklycoordinating anions and/or to coordinate, albeit weakly, to the lithiumcations of lithium salts of weakly coordinating anions; 2) ability tomaintain low glass-transition temperatures with varying amounts oflithium salts dissolved therein; and 3) the ability to possess highelectrical conductivities, especially high lithium-ion conductivities,i.e., higher than lithium triflate/polymer mixture at a giventemperature). Exemplary polymers useful for the present inventioninclude polyethylene glycol; polyethylene; polypropylene; polystyrene;polybutadiene; poly(vinyl fluoride); polychloroprene; poly(alkylsiloxane) such as poly(dimethylsiloxane); poly(vinyl chloride);poly(ethylene imine); and poly(alkylene oxide) such as poly(propyleneoxide), amorphous poly(ethylene oxide) and poly(ethylene oxide).Preferably the polymer is selected from the group consisting ofamorphous polyethylene oxide (aPEO), poly(alkylene oxide), poly(alkylsiloxane), poly(vinyl fluoride), poly(vinyl chloride), polychloroprene,polybutadiene, polyethylene and poly propylene; more preferably from thegroup consisting of aPEO, poly(vinyl fluoride), poly(vinyl chloride),polychloroprene, polybutadiene, polyethylene and polypropylene; and mostpreferably from the group consisting of aPEO, polybutadiene,polyethylene and polypropylene.

The present invention also includes salt-in-polymer electrolytes havingalkali metal salts containing the polyfluorinated anions of the presentinvention. Compounds containing these polyfluorinated anions havesuperior glass transition temperatures, impedance measurements andcation transference numbers than compounds containing other anions.

The polyfluorinated anions of the present invention can also be used asco-catalysts for activating transition-metal-catalyzed olefinpolymerization and as counterions for polymerization photoinitiators.

Additional objects, advantages, and novel features of this inventionwill become apparent to those skilled in the art upon examination of thefollowing examples thereof, which are not intended to be limiting.

EXAMPLES Example 1

Synthesis of LiB(C₆F₅)₃(HFIP)

B(C₆F₅) (0.0256 g, 0.05 mmol) and LiHFIP (0.0087 g, 0.05 mmol) weredissolved in 5 mL of DME to make a clear, colorless solution.

Example 2

Synthesis of LiB(C₆F₅)(DPTE)

B(C₆F₅) (0.0256 g, 0.05 mmol) and LiDPTE (0.0129 g, 0.05 mmol) weredissolved in 5 mL of DME to make a clear, colorless solution.

Example 3

Synthesis of LiB(C₆F₅)₃(PFTB)

B(C₆F₅) (0.0256 g, 0.05 mmol) and LiPFTB (0.0121 g, 0.05 mmol) weredissolved in 5 mL of DME to make a clear, colorless solution.

Example 4

Synthesis of LiAl(DPTE)₄

Hexane (40 mL) was added to LiAlH₄ (0.0188 g, 0.4955 mmol) to make asuspension. To this was added H(DPTE) (0.500 g, 1.982 mmol) as a hexanesolution (10 mL). The reaction mixture was stirred for 4 day at roomtemperature under an argon atmosphere, after which time a considerableamount of a white solid material was present in a clear and colorlesssolution. The mixture was filtered through a medium frit. The whitesolid was washed with hexane, then dissolved in toluene. Toluene wasremoved under vacuum to leave a white solid that was heated at 105° C.for 18 h. A ¹H NMR spectrum of this white solid revealed thatapproximately 3 mol-% of the alcohol H(DPTE) still remained, but thecompound LiAl(DPTE)₄ was otherwise pure.

¹H NMR (C₆D₆/C₆F₆) δ7.26 (d, 16 H) , 7.00 (m, 24 H). ¹⁹F NMR(C₆D₆/C₆F₆)δ−72.40 (s). Low Resolution mass spectrum (negative ion electrospray,CH₃CN solution): m/z 1031 (M-Li)⁻; calc'd for C₅₆H₄₀AlF₁₂O₄ 1031.6.

Example 5

Synthesis of Li(DME)₂Al(TFTB)₄

Hexane (30 mL) was added to LiAlH₄ (0.0976 g, 2.57 mmol) to make asuspension. To this was added H(TFTB) (1.3155 g, 10.28 mmol) as a hexanesolution (20 mL). The reaction mixture was stirred for 3 day at roomtemperature then at reflux for 3 days under an argon atmosphere. Afterthis time almost no solid was present in solution. The mixture wasfiltered through a medium frit, to leave an off-white solid and aslightly tan, clear solution. Hexane was removed from the latter undervacuum to leave a white solid. This was sublimed at 90° C. under vacuumto yield a white powder. The solid was dissolved in DME and stirred for2 h, after which time solvent was removed to yield a white powder.

¹H NMR (C₆D₆/C₆F₆) δ2.89 (DME, s, 6 H), 2.68 (DME, s, 4 H), 1.53 (s, 12H). ¹⁹F NMR(C₆D₆/C₆F₆) δ−84.62 (s).

Example 6

Synthesis of LiAl(HFIP)₄

Freon-113 (40 mL) was added to LiAlH₄ (0.1630 g, 4.29 mmol) to make asuspension. This was cooled to 0° C. in an ice bath, and H(HFIP) (2.8826g, 17.16 mmol) was added dropwise as a solution in 10 mL Freon-113. Thismixture was stirred at 0° C. for 24 h, then at room temperature for 4days. After this time, the solution was white and cloudy. Freon-113 wasremoved under vacuum to leave a white solid, which was found to be 97.4%pure by ¹⁹F NMR.

¹H NMR (CD₃CN/C₆F₆) δ4.6 (m, 4 H). ¹⁹F NMR(CD₃CN/C₆F₆) δ−76.15 (d). LowResolution mass spectrum (negative ion electrospray, CH₃CN solution):m/z 694.9 (M-Li)⁻; calc'd for C₁₂H₄AlF₂₄O₄ 695.1.

Example 7

Synthesis of LiB(HFPOP)₂

H₂(HFPOP) (2.0029 g, 7.7 mmol), LiOH.H₂O (0.1541 g, 3.67 mmol), andB(OH)₃ (0.2267, 3.67 mmol) were dissolved in 115 mL distilled water.Under an argon atmosphere, the mixture was stirred at 105° C. for 18 h.After this time, the solution was clear and colorless. It was opened toair, and water was removed using a rotary evaporator to leave a clear,colorless oil. This was first dried by azeotropic distillation withtoluene to leave a white powder, followed by heating at 197° C. undervacuum (10⁻³ torr) for a period of 18 h. Yield: 1.7856 g (91%) isolatedas a white solid.

¹H NMR (CD₃CN/C₆F₆) δ7.37 (d, 2 H), 7.24 (t, 2 H), 6.79 (t, 2H), 6.7 (d,2 H). ¹⁹F NMR(CD₃CN/C₆F₆) δ−75.00 (s). Low Resolution mass spectrum(negative ion electrospray, CH₃CN solution): m/z 527.1 (M-Li)⁻; calc'dfor C₁₈H₈BF₁₂O₄ 527.0.

Example 8

Synthesis of LiB(HFAPOP)₂

LiOH.H₂O (0.1522 g, 3.62 mmol) and B(OH)₃ (0.2241 g, 3.62 mmol) weredissolved in 115 mL distilled water and heated at reflux for 18 h.H₂(HFAPOP) (2.5120 g, 7.61 mmol) was then added as a solid along withdiethyl ether (15 mL). This mixture was heated to 100° C. and stirredfor 18 h. After this time, the reaction mixture was a clear andcolorless solution. Diethyl ether and water were removed using a rotaryevaporator to leave a clear, colorless oil. This was first dried byazeotropic distillation with toluene to leave an off-white powder,followed by heating at 104° C. under high-vacuum conditions (10⁻⁵ torr)for 7 days. Yield: 1.9749 g (82%) isolated as an off-white solid.

¹H NMR (C₆D₆/C₆F₆) δ7.37 (m, 2 H), 7.133 (s, 1 H), 7.127 (s, 1 H), 2.07(s, 6 H), 1.27 (s, 18 H). ¹⁹F NMR(C₆D₆/C₆F₆) δ−72.81 (m), −76.44 (m).Low Resolution mass spectrum (negative ion electrospray, CH₃CNsolution): m/z 667.3 (M-Li)⁻; calc'd for C₂₈H₂₈BF₁₂O₄ 667.1.

Example 9

Synthesis of LiB(HFTPOP)₂

LiOH.H₂O (0.156 g, 3.72 mmol) and B(OH)₃ (0.230 g, 3.72 mmol) weredissolved in 50 mL distilled water and heated at reflux for 1 h. Thecompound H₂(HFTPOP) (2.45 g, 7.44 mmol) was then added as a solid alongwith diethyl ether (10 mL). This mixture was heated to 100° C. andstirred for 18 h. After this time, the reaction mixture was a clear andcolorless solution. Diethyl ether and water were removed using a rotaryevaporator to leave a clear, colorless oil. This was first dried byazeotropic distillation with toluene, followed by heating at 190° C.under high-vacuum conditions (10⁻³ torr) for 18 h. Yield: 2.08 g (87%).

¹H NMR (CD₃CN/C₆F₆) δ7.12 (m, 2 H). ¹⁹F NMR(CD₃CN/C₆F₆) δ−75.42 (s),−148.75 (m), −157.38 (m). Low Resolution mass spectrum (negative ionelectrospray, CH₃CN solution): m/z 634.8 (M-Li)⁻; calc'd for C₁₈H₂BF₁₈O₄635.0.

Example 10

This example illustrates a method for preparing salt-in-polymerelectrolytes containing the polyfluorinated anion of the presentinvention.

Samples of aPEO containing different stoichiometric amounts ofLiNb(HFIP)₆ were prepared as follows. A sample of the polymer (typically0.13 g, 3.0 mmol ether-oxygen atoms) was mixed with tetrahydrofuran (7mL). The resulting mixture was mixed with a tetrahydrofuran solutioncontaining varying amounts of LiNb(HFIP)₆ so that theether-oxygen/lithium molar ratio was 12, 24, or 30. The reaction mixturewas stirred for 15 hours, after which time a colorless homogeneoussolution was observed. Volatiles were removed from the reaction mixtureby vacuum evaporation, resulting in a clear, colorless, rubbery solid onthe walls of the flask. The rubbery solid was heated under vacuum at 60°C. for 12 hours to ensure complete removal of tetrahydrofuran. The threeclear, colorless, rubbery, salt-in-polymer electrolytes prepared in thisway were aPEO₁₂LiNb(HFIP)₆, aPEO₂₄LiNb(HFIP)₆, and aPEO₃₀LiNb(HFIP)₆.

Example 11

Synthesis of LiAl[O(C₆H₄)C(CF₃)₂O]₂

About 0.515 g of HO(C₆H₄)C(CF₃)₂OH (1.98 mmol) and 0.155 g of LiAlH₄(4.09 mmol) were mixed in toluene and stirred for 140 h. The reactionmixture was filtered through a Schlenk filter with Celite. The filtratewas concentrated under vacuum to leave a brown solid.

¹H NMR (C₆D₆) δ7.76 (doublet, 1 H), 7.37 (doublet, 1 H), 6.93 (triplet,1 H), 6.73 (triplet, 1 H), 6.65 (triplet, 1 H), 6.56 (triplet, 1 H),6.45 (doublet, 1 H), 6.03 (doublet, 1 H). ¹⁹F NMR (C₆D6) δ−72.47(multiplet), −74.06 (multiplet), −78.15 (multiplet), −78.75 (multiplet).

The foregoing discussion of the invention has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the invention to the form or forms disclosed herein. Althoughthe description of the invention has included description of one or moreembodiments and certain variations and modifications, other variationsand modifications are within the scope of the invention, e.g., as may bewithin the skill and knowledge of those in the art, after understandingthe present disclosure. It is intended to obtain rights which includealternative embodiments to the extent permitted, including alternate,interchangeable and/or equivalent structures, functions, ranges or stepsto those claimed, whether or not such alternate, interchangeable and/orequivalent structures, functions, ranges or steps are disclosed herein,and without intending to publicly dedicate any patentable subjectmatter.

What is claimed is:
 1. A compound comprising a monoanion of the formula:

wherein M₁ is a transition metal, or a Group III, IV or V elementprovided M₁ is not Cu; each Z is independently O, S, or NR₆R₇; each X isindependently a halide; each R₁ is independently a bond or C₁-C₄alkylene; each of R₂, R₃ and R₄ is independently H, F, fluorinatedC₁-C₁₀ alkyl, fluorinated C₄-C₂₀ aryl, C₃-C₁₀ cycloalkyl, fluorinatedC₃-C₁₀ cycloalkyl, C₁-C₁₀ alkyl or C₄-C₂₀ aryl, provided at least one ofR₂, R₃ and R₄ is F, fluorinated C₁-C₁₀ alkyl, fluorinated C₃-C₁₀cycloalkyl, or fluorinated C₄-C₂₀ aryl; each R₅ is independentlyfluorinated C₁-C₁₀ alkyl, fluorinated C₄-C₂₀ aryl, C₄-C₂₀ aryloxide,fluorinated C₄-C₂₀ aryloxide, C₁-C₁₀ alkoxide or fluorinated C₁-C₁₀alkoxide; each of R₆ and R₇ is independently H or C₁-C₁₀ alkyl; and eachof a, b and c is independently an integer from 0 to 4, provided the sumof a, b and c is an integer from 2 to 8; and provided that when R₂ is afluorinated C₁-C₄ alkyl, R₁ is a bond, b, and c are 0, and R₃ is C₁-C₁₀alkyl or fluorinated C₁-C₁₀ alkyl then R₄ is F, fluorinated C₁-C₁₀ alkylor fluorinated C₄-C₂₀ aryl.
 2. The compound of claim 1, wherein M₁ isselected from the group consisting of Al, B, V, Ti, Si, Zr, Cu, Ge, Sn,Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf and Sb.
 3. The compound of claim 2,wherein M₁ is selected from the group consisting of Al, B, Nb and Ta. 4.The compound of claim 3, wherein M₁ is selected from the groupconsisting of Al and B.
 5. The compound of claim 1, wherein X is F. 6.The compound of claim 1, wherein R₅ is pentafluorophenyl.
 7. Thecompound of claim 1, wherein Z is O and R₁ is a bond.
 8. The compound ofclaim 7, wherein R₂ is trifluoromethyl, and each of R₃ and R₄ isindependently phenyl or methyl; R₂, R₃ and R₄ are trifluoromethyl; R₂ istrifluoromethyl, R₃ is phenyl, and R₄ is phenyl or pentafluorophenyl; orR₂ and R₃ are phenyl, and R₄ is pentafluorophenyl.
 9. The compound ofclaim 1, wherein R₅ is 2-trifluoromethyl-phenoxide,3-trifluoromethylphenoxide, 4-trifluoromethylphenoxide,pentafluorophenoxide, or pentafluorophenyl.
 10. The compound of claim 1,wherein the sum of a, b and c is
 4. 11. The compound of claim 1, whereinZ is O and R₁ is methylene.
 12. The compound of claim 11, wherein b andc are 0, a is 4 and R₂, R₃ and R₄ are F.
 13. An electrolyte for anelectrochemical device comprising the compound of claim
 1. 14. Theelectrolyte of claim 13, wherein the counter cation of said monoanion islithium.
 15. A compound comprising an anion of the formula:

wherein M₁ is a transition metal, or a Group III, IV or V element; L isa halide, C₁-C₁₀ alkyl, fluorinated C₁-C₁₀ alkyl, C₄-C₂₀ aryl,fluorinated C₄-C₂₀ alkyl or a moiety of the formula —Z₃—R₁₁; d is aninteger from 0 to 4; e is an integer from 1 to 3; the sum of d and e isan integer from 1 to 6; n is 1 or 2; each of Z₁, Z₂ and Z₃ isindependently O, S, or NR₆R₇; each of R₆ and R₇ is independently H orC₁-C₁₀ alkyl; each R₉ is independently C₁-C₃₀ alkylene, fluorinatedC₁-C₃₀ alkylene, substituted C₁-C₃₀ alkylene, C₃-C₁₀ cycloalkylene,fluorinated C₃-C₁₀ cycloalkylene, C₄-C₂₀ arylene or fluorinated C₄-C₂₀arylene; each of R₈ and R₁₀ is a bond, or a moiety of the formula—[C(R₁₂R₁₃)]_(x)—; each x is independently an integer from 1 to 4; eachof R₁₂ and R₁₃ is independently H, F, C₁-C₄ alkyl or fluorinated C₁-C₄alkyl; and each R₁₁ is independently C₁-C₁₀ alkyl, fluorinated C₁-C₁₀alkyl, C₄-C₂₀ aryl, or fluorinated C₄-C₂₀ aryl; provided at least one ofR₈ and R₁₀ is a moiety of the formula —C(R₁₂R₁₃)— and at least one ofR₁₂ and R₁₃ is F or fluorinated C₁-C₄ alkyl.
 16. The compound of claim15, wherein M₁ is selected from the group consisting of Al, B, V, Ti,Si, Zr, Ge, Sn, Cu, Y, Zn, Ga, Nb, Ta, Bi, P, As, Sc, Hf and Sb.
 17. Thecompound of claim 16, wherein M₁ is selected from the group consistingof Al, B, Nb and Ta.
 18. The compound of claim 17, wherein M₁ isselected from the group consisting of Al and B.
 19. The compound ofclaim 15, wherein R₁₂ and R₁₃ are fluorinated C₁-C₄ alkyl.
 20. Thecompound of claim 19, wherein R₁₂ and R₁₃ are trifluoromethyl.
 21. Thecompound of claim 15, wherein the sum of d and e is 2 or
 4. 22. Thecompound of claim 15, wherein n is 1, Z₁ and Z₂ are O, R₈ is a moiety ofthe formula —C(R₁₂R₁₃)—, R₁₀ is a bond, and R₁₂ and R₁₃ aretrifluoromethyl.
 23. The compound of claim 15, wherein n is 1 and the—Z₁—R₈—R₉—R₁₀—Z₂— moiety comprises:

wherein each of R₁₄, R₁₅, R₁₆, and R₁₇ is independently H, C₁-C₁₀ alkyl,fluorinated C₁-C₁₀ alkyl, C₄-C₂₀ aryl, or fluorinated C₄-C₂₀ aryl. 24.The compound of claim 23, wherein R₁₄ and R₁₇ are trifluoromethyl, R₁₅is H, and R₁₆ is phenyl.
 25. The compound of claim 15, wherein d is 0and e is
 2. 26. The compound of claim 15, wherein d is 2 and e is
 2. 27.The compound of claim 15, wherein L is F.
 28. The compound of claim 15,wherein R₉ is C₄-C₂₀ arylene or fluorinated C₄-C₂₀ arylene.
 29. Anelectrolyte for an electrochemical device comprising a compound of claim15.